The Effect of Ovariectomy on Lipoprotein Metabolism during a Period of One Year1)

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Abstract
In a follow-up study over one year the influence of sex hormones on lipoprotein metabolism in women after ovariectomy was investigated. During this relatively long period we could observe several changes of lipid and apolipoprotein levels in serum which may be caused by adaptive processes after withdrawal of sex hormones. The first phase of variation of lipids and apolipoproteins (2 weeks after ovariectomy) is strongly influenced by the operation trauma and characterized by a decrease of apo A-I, apo A-II, TC levels and an increase of the triglyceride level. The second phase (6—18 weeks after operation) shows an increase of the levels of apolipoprotein of HDL (apo A-I and apo A-II) and also apo C-II and apo C-III. The pattern in the third phase (one year after operation) differs from that of the two earlier phases and is similar to that in the natural postmenopausal state (elevation of apo B, TC, nonsignificant elevation of apo A-I and significant elevation of apo A-II). It seems that ovariectomy causes permanent changes of the LDL-level whereas the fluctuation of HDL is temporary. The late changes in the lipoprotein spectrum following ovariectomy in the reported direction may be important for the increase of ischemic heart disease observed by many investigators.